Writing stem for writing instruments

ABSTRACT

A writing stem for writing instruments which can give an appropriate cushion effect to the gripping thumb and fingers includes a grip section formed of an elastic material. A plurality of protruding pieces that can be bent by the gripping force are formed in parallel to one another on the surface of the grip section, including a portion about 30 mm to about 40 mm behind the tip of the writing instrument, and this plurality of protruding pieces are formed over a length equivalent to about ⅔ of the overall length of the grip section in the longitudinal direction.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a writing stem for writinginstruments, having, for example, a grip section comprising an elasticmaterial.

[0003] 2. Description of the Related Art

[0004] Known examples of writing instruments of this kind include afinger gripping device, disclosed for instance in U.S. Pat. No.4,601,598, incorporated by reference in its entirety. The grippingdevice described herein is formed as a barrel made of a flexiblematerial, on whose surface a plurality of circular ribs are formed.

BRIEF SUMMARY OF THE INVENTION

[0005] However, since such a rib of a grip according to the conventionalstructure has little level difference between the crests and grooves ofits ribs, and is mainly intended to achieve a cushion effect with theflexibility of its flexible material (e.g., the flexible composition ofthe material itself), no sufficient cushion effect can be achieved,resulting in fatigue of a user's thumb and fingers.

[0006] The present invention is directed to solving this problem andothers found in the conventional structure, and an object thereof is toprovide a writing stem for writing instruments having a proper andsufficient cushion effect for a user's gripping thumb and fingers.

SUMMARY OF THE INVENTION

[0007] In order to attain the above-described object and others,according to the invention, there is provided a writing stem for writinginstruments, having a grip section including an elastic material, with aplurality of protruding pieces formed on the surface of the grip sectionthat can be bent by a gripping force. The bending of the protrudingpieces can provide the user with a cushioned effect (e.g., a “softfeel”). Since only the portions of the writing stem where the user'sthumb and fingers actually come into contact therewith are compressed,the user's grip will be comfortable and non-fatiguing.

[0008] Optionally, it is possible to form clusters of the plurality ofprotruding pieces on the surface of the grip section including a portionpositioned substantially approximately 30 to 40 mm behind the tip of thewriting instrument, and the length of these clusters in the axialdirection can be made equivalent to about ⅔of the overall length of thegrip section in the axial direction. By forming these clusters of theplurality of protruding pieces over a length equivalent to about ⅔of theoverall length of the grip section in the axial direction, a cushioneffect and a non-slip effect can be achieved on and around the portionwith which the user's thumb and fingers actually come into contact,resulting in a writing stem which causes the user to feel no excessivesoftness but a proper degree of firmness. Thus, the user is not fatiguedeven after continuous writing for many hours. The clusters on the gripsection may be unified to cover the section all around. However, morepreferably, three such clusters may be provided in the circumferentialdirection separately from one another, which correspond to the user'sthumb and the fingers (e.g., the index finger and the middle finger)gripping the stem.

[0009] Optionally, it is also possible to vary the height of theplurality of protruding pieces at regular spatial intervals, to vary thedepth of grooves between adjacent protruding pieces at regular spatialintervals, to vary the thickness of the plurality of protruding piecesat regular spatial intervals, or to vary the spacing between adjacentprotruding pieces at regular spatial intervals. Since it is thereby madepossible to vary a degree of bending ease of the plurality of protrudingpieces by use of a regular spatial period, portions where the protrudingpieces are difficult to bend are formed at regular intervals. Thus, awriting stem is formed which causes the user to feel no excessivesoftness but a proper degree of firmness, and does not fatigue the usereven after continuous writing for many hours.

[0010] Optionally, it is also possible to gradually increase the heightof the plurality of protruding pieces from the forward end and from therearward end of the writing stem to an intermediate portion in the axialdirection of the grip section, so that the height of the plurality ofprotruding pieces is the highest at the intermediate portion. This makesthe portion other than the intermediate portion, which is unlikely to begripped by the user, difficult to bend, and the intermediate potionwhich is likely to be gripped by the user, easy to bend, and enables theuser to grip the intermediate portion whose relative hardness is mostpreferable for the user, resulting in a writing stem which does notfatigue the user even after continuous writing for many hours.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a vertical cross sectional view (along the line 1-1in FIG. 2) of a first embodiment of the writing stem for a writinginstrument according to the present invention;

[0012]FIG. 2 is a plan view of the embodiment illustrated in FIG. 1;

[0013]FIG. 3 shows a cross sectional view along the line 3-3 in FIG. 1;

[0014]FIG. 4 shows a vertical half cross-sectional view of an essentialpart of a second embodiment of the writing stem for a writing instrumentaccording to the present invention;

[0015]FIG. 5 shows a vertical half cross-sectional view of an essentialpart of a third embodiment of the writing stem for a writing instrumentaccording to the present invention;

[0016]FIG. 6 shows a vertical half cross-sectional view of an essentialpart of a fourth embodiment of the writing stem for a writing instrumentaccording to the present invention;

[0017]FIG. 7 shows a vertical half cross-sectional view of an essentialpart of a fifth embodiment of the writing stem for a writing instrumentaccording to the present invention;

[0018]FIG. 8 shows a vertical half cross-sectional view of an essentialpart of a sixth embodiment of the writing stem for a writing instrumentaccording to the present invention; and

[0019]FIG. 9 shows a vertical half cross-sectional view of an essentialpart of a seventh embodiment of the writing stem for a writinginstrument according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Preferred embodiments of the present invention will be describedbelow with reference to the accompanying drawings.

First Embodiment

[0021]FIGS. 1 through 3 illustrate the first embodiment of theinvention. In the figures, reference numeral 10 denotes a writinginstrument, which is represented by a propelling (e.g., mechanical)pencil here. However, the invention is applicable to ball point pens,felt tip pens, eyeliners, computer pens, other writing instruments, andother hand-held instruments such as devices used in the medical field,light pens, laser pointers, etc.

[0022] The writing stem 11 of the writing instrument 10 comprises afront nose 12, a front barrel 14, a rear barrel 16 screwed onto thefront barrel 14, and a grip section 18 fitted around the front barrel 14which serves as a grip section. Within the writing stem 11 is disposed aknown lead feeding mechanism 20, and within the front nose 12 is fixed atip pipe 22. Alternatively, this tip pipe 22 may be retractable by thelead feeding mechanism 20.

[0023] The grip section 18 comprises an elastic material, such assynthetic rubber, silicon rubber or thermoplastic elastomer. Though thegrip section 18 is shown separated from the front barrel 14 in thisexample, the grip section can be integrally molded with the front barrel14 by dichromatic molding or otherwise. The overall length of the gripsection 18 may preferably be substantially approximately 3/10 toapproximately 4/10 of that of the writing stem 11. The hardness of thegrip section 18 is recommended to be between about 35 and about 85 inShore A hardness because of ease of molding or manufacturing, producingor material cost, and elasticity, but may also be appropriately chosenfrom outside this recommended range.

[0024] A plurality of protruding pieces 18 a, which can be bent by agripping force, are formed substantially in parallel to one another onthe surface of the grip section 18, including a portion positioned about30 mm to about 40 mm behind the front tip of the tip pipe 22, whichcomprises the tip of the writing instrument 10. A plurality (e.g.,preferably three) clusters of these protruding pieces 18 a are providedapproximately 120 degrees apart from one another in the circumferentialdirection of the grip section 18, and the length of each cluster in theaxial direction is equivalent to about ⅔of the overall length of thegrip section 18. The phrase “equivalent to about ⅔of the overall length”here means that the length of each cluster in the axial direction isbetween about 6.0/10 to about 7.0/10 of the overall length of the gripsection 18. The protruding pieces 18 a may preferably protrude in thedirection of the external diameter by about 1.0 to about 2.5 times thethickness of the grip section 18 where no protruding piece 18 a ispresent, but their protruding height can also be chosen from outsidethis range.

[0025] The user, when gripping the writing instrument 10, usually holdsthe thumb and fingers (e.g., index finger and middle finger) about 30 toabout 40 mm behind the writing tip. Therefore, the protruding pieces 18a are arranged in a position where the thumb and these fingers can beeffectively placed. Further to match this positioning, the outsidediameter along the envelope of the grip section 18 is set to be thesmallest in a position about 30 to about 40 mm behind the tip of thewriting instrument 10.

[0026] Each protruding piece 18 a extends in a direction substantiallyorthogonal to the axis of the writing instrument 10, and itscross-sectional shape is so curved as to become thinner toward the apex,thereby facilitating manufacturing (e.g., release from a die) when thegrip section 18, including the protruding piece, is molded.

[0027] With the writing instrument having such a configuration, when theuser holds the grip section 18 with the user's thumb and fingers, thegripping force bends the protruding pieces 18 a to provide a cushioneffect as well as a non-slip effect. Unlike in a configuration whereprotruding pieces 18 a are uniformly arranged over substantially theentire grip section 18, the protruding pieces 18 a are formed over alength in the longitudinal direction equivalent to about ⅔of the overalllength of the grip section, including the portion about 30 mm to about40 mm behind the tip of the writing instrument, so that the user willnot feel excessive softness by a chain collapse (bending) of many of theprotruding pieces. Instead, the user senses a proper degree of firmness,and is not fatigued even after continuous writing for many hours. Theformation of protruding pieces over about ⅔of the length of the gripsection over a length in the longitudinal direction (e.g. in a ratio ofabout 6.0/10 to about 7.0/10 of its length) feels very pleasant to theuser.

Second Embodiment

[0028] Next, FIG. 4 shows a vertical half cross-sectional view of thesecond embodiment of the invention, in which the remaining part of thewriting stem is the same as the corresponding part of the firstembodiment, and accordingly its illustration is omitted. Forconsistency, the same members as in the first embodiment are assignedthe same reference numerals, and for brevity their description is alsoomitted.

[0029] On the surface of a grip section 28, there are formed a pluralityof protruding pieces 28 a substantially in parallel to one another, andthe heights of these protruding pieces 28 a alternately differ (e.g.,higher protruding pieces 28 a 1 and lower protruding pieces 28 a 2 arearranged in alternate repetition). As the higher protruding pieces 28 a1 are easy to bend while the lower protruding pieces 28 a 2 aredifficult to bend, a degree of bending ease of the protruding pieces 28a varies at regular spatial intervals.

[0030] A writing stem having this configuration provides the sameeffects and advantages as the first embodiment. When the user holds thegrip section 28 with the user's thumb and fingers, the gripping forcebends the protruding pieces 28 a. As the lower protruding pieces 28 a 2,which are difficult to bend, are disposed at regular intervals, unlikein a configuration where equally tall protruding pieces are disposedover the substantially entire grip section 28, the user will not feelexcessive softness by a chain collapse (bending) of many of theprotruding pieces. Instead, the user senses a sufficient amount ofresilience (e.g., hardness), and is not fatigued even after continuouswriting for many hours.

[0031] This variation in height may also occur at intervals of two ormore protruding pieces instead of one as illustrated.

Third Embodiment

[0032] Next, FIG. 5 shows a vertical half cross sectional view of anessential part of the third embodiment of the invention, in which theremaining part of the writing stem is the same as the corresponding partof the first embodiment, and accordingly its illustration is omitted.The same members as in the first embodiment are assigned the samereference numerals, and their description is also omitted.

[0033] On the surface of a grip section 32 in this embodiment, there areformed a plurality of protruding pieces 32 a in parallel to one another,and the depths of grooves between these adjacent protruding pieces 32 aalternately differ (e.g., deeper grooves 32 b 1 and shallower grooves 32b 2 are arranged in alternate repetition). At a deeper groove 32 b 1,the adjacent protruding pieces 32 a are easy to bend toward the groove32 b 1 while at a shallower groove 32 b 2, the adjacent protrudingpieces 32 a are difficult to bend toward the groove 32 b 2, so that adegree of bending ease of the protruding pieces 32 a varies at regularspatial intervals.

[0034] A writing stem having this configuration provides the sameeffects as the second embodiment. When the user holds the grip section32 with their thumb and fingers, the gripping force bends the protrudingpieces 32 a. At this time, as the shallower grooves 32 b 2, in which theprotruding pieces 32 a are difficult to bend, are disposed at regularintervals, unlike in a configuration where protruding pieces adjacent toequally deep grooves are disposed over the substantially whole gripsection 32, the user will not feel excessive softness by a chaincollapse (bending) of many of the protruding pieces, but senses a properdegree of hardness, and is not fatigued even after continuous writingfor many hours.

[0035] This variation in groove depth also may occur at the intervals oftwo or more grooves instead of one as illustrated.

Fourth Embodiment

[0036] Next, FIG. 6 shows a vertical half cross sectional view of anessential part of a fourth embodiment of the writing stem for writinginstruments according to the invention, in which the remaining part ofthe writing stem is the same as the corresponding part of the firstembodiment, and accordingly its illustration is omitted. The samemembers as in the first embodiment are assigned the same referencenumerals, and their description is also omitted.

[0037] On the surface of a grip section 38 in this embodiment, there areformed a plurality of protruding pieces 38 a substantially in parallelto one another, and the thickness of these protruding pieces 38 aalternately differ (e.g., thicker protruding pieces 38 a 1 and thinnerprotruding pieces 38 a 2 are arranged in alternate repetition). As thethicker protruding pieces 38 a 1 are difficult to bend while the thinnerprotruding pieces 38 a 2 are easy to bend, a degree of bending ease ofthe protruding pieces 38 varies at regular spatial intervals.

[0038] A writing stem having this configuration provides the sameeffects as the second embodiment. When the user holds the grip section38 with the user's thumb and fingers, the force of gripping bends theprotruding pieces 38 a. As the thicker protruding pieces 38 a 1, equallythick protruding pieces are disposed over the substantially whole gripsection 38, the user will not feel excessive softness by a chaincollapse (bending) of many of the protruding pieces, but senses a properdegree of hardness, and is not fatigued even after continuous writingfor many hours.

[0039] This variation in thickness may as well occur at intervals of twoor more protruding pieces instead of one as illustrated.

Fifth Embodiment

[0040] Next, FIG. 7 shows a vertical half cross sectional view of anessential part of a fifth embodiment of the writing stem for writinginstruments according to the invention, in which the part of the writingstem is the same as the corresponding part of the first embodiment, andaccordingly its illustration is omitted. The same members as in thefirst embodiment are assigned the same reference numerals, and theirdescription is also omitted.

[0041] On the surface of a grip section 48 in this embodiment, there areformed a plurality of protruding pieces 48 a substantially in parallelto one another, and the intervals between adjacent protruding pieces 48a alternately differ (e.g., protruding pieces 48 a with a wider interval48 b 1 between them and protruding pieces 48 a with a narrower interval48 b 2 between them are arranged in alternate repetition). At a widerinterval 48 b 1, the adjacent protruding pieces 48 a are easy to bendtoward the interval 48 b 1 while at a narrower interval 48 b 2, theadjacent protruding pieces 48 a are difficult to bend toward theinterval 48 b 2, so that a degree of bending ease of the protrudingpieces 48 a varies at regular intervals.

[0042] A writing stem having this configuration provides the sameeffects as the second embodiment. When the user holds the grip section48 with the user's thumb and fingers, the gripping force bends theprotruding pieces 48 a. At this time as the narrower intervals 48 b 2,in which the protruding pieces 48 a are difficult to bend, are disposedat regular intervals, unlike in a configuration where protruding piecesare disposed at equal intervals over the substantially whole gripsection 48, the user will not feel excessive softness by a chaincollapse (bending) of many protruding pieces, but senses a proper degreeof hardness, and is not fatigued even after continuous writing for manyhours.

[0043] This variation in spacing may as well occur at intervals of twoor more in-between spaces, instead of one as illustrated.

Sixth Embodiment

[0044] Next, FIG. 8 shows a vertical half cross-sectional view of anessential part of a sixth embodiment of the writing stem for writinginstruments according to the invention, in which the remaining part ofthe writing stem is the same as the corresponding part of the firstembodiment, and accordingly its illustration is omitted. The samemembers as in the first embodiment are assigned the same referencenumerals, and their description is also omitted.

[0045] On the surface of a grip section 58 in this embodiment, there areformed a plurality of protruding pieces 58 a substantially in parallelto one another, and the heights of these protruding pieces 58 agradually increase toward the front tip of the writing stem. As tallerprotruding pieces 58 a 1 are easier to bend, the cushion effectincreases toward the front tip of the writing stem.

[0046] A writing stem having this configuration provides the sameeffects as the first embodiment. When the user holds the grip section 58with the user's thumb and fingers, the gripping force bends theprotruding pieces 58 a. The grip section 58 has a greater cushion effecttoward the front tip as stated above. Thus, the user, when writing, cangrip the position where a cushion effect of his or her own preferencecan be achieved, around the portion about 30 mm to about 40 mm behindthe front tip of the tip pipe 22 which constitutes the tip of the stem.Unlike a configuration where equally tall protruding pieces are disposedover the whole grip section, the user will not feel excessive softnessby a chain collapse (bending) of many protruding pieces, but senses aproper degree of hardness, and is not fatigued even after continuouswriting for many hours.

[0047] Incidentally, although the second through sixth embodimentdescribed above have protruding pieces all over the grip section, theinvention is not limited to this disposition, but obviously aconfiguration in which protruding pieces are formed on a limited part ofthe grip section is also possible.

Seventh Embodiment

[0048] Next, FIG. 9 shows a vertical half cross-sectional view of anessential part of a seventh embodiment of the writing stem for writinginstruments according to the invention, in which the remaining part ofthe writing stem is the same as the corresponding part of the firstembodiment, and accordingly its illustration is omitted. The same memberas the first embodiment are assigned the same reference numerals andtheir description is also omitted.

[0049] In the seventh embodiment, on the surface of a grip section 68, aplurality of protruding pieces 68 a are formed substantially in parallelto one another. The heights of these protruding pieces 68 a are thehighest at an intermediate portion 68 b in the axial direction of thegrip section 68. The heights of these protruding pieces 68 a graduallyincrease from a front end of the entire portion where the protrudingpieces 68 a are formed to the intermediate portion 68 b and from a rearend of the entire portion where the protruding pieces 68 a are formed tothe intermediate portion 68 b.

[0050] The intermediate portion 68 b is preferably arranged in aposition where tips of the thumb and the index finger, and the middlefinger are easily placed when the user is writing. More preferably, theintermediate portion 68 b is arranged about 30 mm to about 40 mm behindthe tip of the writing instrument as the same reason as that describedin the first smallest in the intermediate portion 68 b.

[0051] Since the taller protruding pieces 68 a are easier to bend, thecushion effect increases at the intermediate portion 68 b (e.g., namely,at or near a portion where tips of the thumb and index finger, and themiddle finger are likely to be placed). Since the heights of theprotruding pieces 68 a other than in the intermediate portion 68 b arelower than the heights of the protruding pieces 68 a in the intermediateportion 68 b, the protruding pieces 68 a in the portion(s) other thanthe intermediate portion 68 b are relatively difficult to bend.

[0052] A writing stem having this configuration provides the sameeffects as the first embodiment. When the user holds the grip section 68with the user's thumb and fingers, the gripping force bends theprotruding pieces 68 a. Thus, the user, when writing, can achieve thecushion effects and a non-slip effect in the intermediate portion 68 b(e.g., namely, at or around a portion where tips of the thumb and indexfinger, and the middle finger are placed). Unlike a configuration whereequally tall protruding pieces are disposed over the whole grip section,the user will not feel excessive softness by a chain collapse (bending)of many protruding pieces, but senses a proper degree of hardness, andis not fatigued even after continuous writing for many hours.

[0053] Incidentally, although the seventh embodiment described above hasprotruding pieces 68 a formed on a part of the grip sectioncorresponding about ⅔length of the grip section, the invention is notlimited to this disposition, but obviously a configuration in whichprotruding pieces are formed all over the grip section 68 is possible.

[0054] Depending on the configurations according to the first throughseventh embodiments, the hardness and thickness of the grip section maybe appropriately selected so as to provide a good grasp of the gripsection.

[0055] While the invention has been described in terms of severalpreferred embodiments, those skilled in the art will recognize that theinvention can be practiced with modification within the spirit and scopeof the appended claims.

What is claimed is:
 1. A writing stem for a writing instrument, having agrip section comprising an elastic material, wherein a plurality ofprotruding pieces that can be bent by a gripping force are formed on asurface of the grip section.
 2. The writing stem for a writinginstrument, according to claim 1 , wherein clusters of said plurality ofprotruding pieces are formed on the surface of the grip sectionincluding a portion positioned substantially about 30 mm to about 40 mmbehind a front tip of the writing instrument, and the length of theseclusters in the axial direction is made equivalent to about ⅔of theoverall length of the grip section in the axial direction.
 3. Thewriting stem for a writing instrument, according to claim 2 , whereinthree said clusters are provided in the circumferential directionseparately from one another.
 4. The writing stem for a writinginstrument, according to claim 1 , wherein a height of said plurality ofprotruding pieces is varied by a regular spatial period.
 5. The writingstem for a writing instrument, according to claim 1 , wherein a depth ofgrooves between adjacent protruding pieces is varied by a regularspatial period.
 6. The writing stem for a writing instrument, accordingto claim 1 , wherein a thickness of said plurality of protruding piecesis varied by a regular spatial period.
 7. The writing stem for a writinginstrument, according to claim 1 , wherein a spacing between adjacentprotruding pieces is varied by a regular spatial period.
 8. The writingstem for a writing instrument, according to claim 1 , wherein a heightof said plurality of protruding pieces is gradually increased toward aforward end of the writing stem.
 9. The writing stem for a writinginstrument, according to claim 1 , wherein a height of said plurality ofprotruding pieces is gradually increased from a forward end of the gripsection and from a rearward end of the grip section to an intermediateportion of the grip section, such that the heights of the protrudingpieces are highest at the intermediate portion.
 10. The writing stem fora writing instrument, according to claim 1 , wherein the elasticmaterial comprises at least one of synthetic rubber, silicon rubber, anda thermoplastic elastomer.
 11. The writing stem for a writinginstrument, according to claim 1 , wherein the hardness of the writingstem lies in a range between about 35 and about 85 in Shore A hardness.12. The writing stem for a writing instrument, according to claim 1 ,wherein said protruding pieces are formed over about ⅔of a length ofsaid grip section in the axial direction thereof.
 13. The writing stemfor a writing instrument, according to claim 1 , wherein a length ofeach cluster of protruding pieces in the axial direction is no less thanabout 3/10 and no more than about 3.5/10 of the overall length of saidgrip section.
 14. The writing stem for writing instrument, according toclaim 1 , wherein said writing stem has a smallest outer diameter at aposition about 30 mm to about 40 mm behind a tip of the writinginstrument.
 15. A stem for a hand held object, comprising: a gripsection formed of an elastic material, wherein a plurality of protrudingpiece are formed on a surface of said grip section.
 16. The stemaccording to claim 15 , wherein said object comprises a writinginstrument.
 17. A hand-held instrument, comprising: a grip sectionformed of an elastic material, wherein a plurality of protruding piecesthat can be bent by a gripping force are formed on a surface of the gripsection, whereby an individual protruding piece of said plurality ofprotruding pieces extends in a direction orthogonal to a longitudinalaxis of the instrument.
 18. The instrument, according to claim 17 ,wherein said individual protruding piece is curved to become thinnertoward an apex of said piece.
 19. The instrument according to claim 17 ,wherein clusters of said plurality of protruding pieces are formed onthe surface of the grip section including a portion positionedsubstantially about 30 mm to about 40 mm behind a front tip of theinstrument, and the length of these clusters in the axial direction ismade equivalent to about {fraction (2/3)}of the overall length of thegrip section in the axial direction.
 20. The instrument according toclaim 19 , wherein three such clusters are provided in thecircumferential direction separately from one another.
 21. Theinstrument, according to claim 17 , wherein a height of said pluralityof protruding pieces is varied by a regular spatial period.